GEOLOGICAL EXPLORATIONS AND LITEKATURE— ISOl. 39 



sodium and potassium, and the other destitute of these elements. From a 

 careful reading of Whittlesey's article it appears that the author is inclined 

 to doubt the sedimentary and metamorphic origin of the Huronian ores 

 and to advocate an eruptive origin for them, as well as for the schists 

 associated with them. 



ISGl. 



Hunt, T. S. Ou some poiuts in American geology. Am. Jour. Sci. (2), Vol. 

 XXXJ, 1861, pages 393-414. 



Hunt reviews the conclusions reached by .studies in the older rock 

 formations of America, and announces that Mr. Alexander Murray, after an 

 examination of the south shore of Lake Superior, had found that the Mar- 

 quette ores, together with the quartzites, conglomerates, limestones, slates, 

 and the "great beds of diorite which we are disposed to regard as altered 

 sediments," all belong to the Huronian series as defined by the Canadian 

 survey, and to that portion of it which is equivalent to ilurchisou's 

 Cambrian in Scotland (p. 394). 



WiNCHBLL, Alexander. First biennial report of the progress of the geolog- 

 ical survey of Michigan. Lansing, 1801. 339 pages. 



By an act approved February 15, 1859, the State of Michigan decided 

 to finish its geological survey begun under Dr. Houghton. Alexander 

 Winchell was appointed State geologist. He published one report, which 

 is devoted almost exclusively to the geology of the Lower Peninsula. In a 

 few sentences the geology of the Upper Peninsula, as outlined by Foster 

 and Whitnev, is described. 



This repoi't constitutes about all of the results of the revivified survey. 

 It was evidently abandoned at the opening of the war, and nothing else 

 was done by the State in the way of geological work in the Upper 

 Peninsula until the second survey was established in 1869. 



1SG3. 



BrasBY, J. J. On the Cambrian and Huronian formations. Quart. Jour. Geo!. 

 Soc, Vol. XIX, 1SG3, pages 36-52. 



Bigsby correlates the Azoic rocks of the south shore of Lake Superior 

 with the Huronian of Canada. He places in this group not only the 



